Clean up forward declarations in Source/modules

Source/modules/webdatabase/SQLStatementBackend.h

 /*
  * Copyright (C) 2007, 2013 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 22 matching lines @@
 #include "wtf/Forward.h"
 #include "wtf/Vector.h"
 #include "wtf/text/WTFString.h"
 
 namespace blink {
 
 class Database;
 class SQLErrorData;
 class SQLResultSet;
 class SQLStatement;
-class SQLTransactionBackend;
 
 class SQLStatementBackend final : public GarbageCollectedFinalized<SQLStatementBackend> {
 public:
     static SQLStatementBackend* create(SQLStatement*,
         const String& sqlStatement, const Vector<SQLValue>& arguments, int permissions);
     void trace(Visitor*);
 
     bool execute(Database*);
     bool lastExecutionFailedDueToQuota() const;
 
@@ skipping 20 matching lines @@
 
     OwnPtr<SQLErrorData> m_error;
     Member<SQLResultSet> m_resultSet;
 
     int m_permissions;
 };
 
 } // namespace blink
 
 #endif // SQLStatementBackend_h